(1) Field of the Invention
The present invention relates to a thermal recording apparatus, and more specifically, to a thermal recording apparatus of a facsimile device.
(2) Description of the Prior Art
FIG. 6 is a side view showing a major portion of the basic structure of a thermal record apparatus termed "thermal printer" or the like. Usually, in a thermal printer, a thermal head 1 is tightly pressed against a thermosensitive paper 3 on a roller 2 to prevent an irregularity in printing density. The thermal head 1 is fixed to a receiving portion 5 of a supporter 4, and a pushing device 6 such as a spring urges the thermosensitive paper 3 against the roller 2. At this time, vertical portions 8 of the supporter 4 hold a rotation shaft 9 of the roller 2 therebetween to keep the thermal head 1 in position. The thermal head 1 is composed of a plurality of heating resistance elements 7 disposed in parallel to the line of the rotation axis of the roller 2. The pushing device 6 applies force at the point on a plane P1 including the line corresponding to the rotation axis 9 and the heating resistance elements 7. The roller 2 has a shape of a right circular cylinder, and is driven by a driving mechanism (not shown) such as a stepping motor, operating synchronously with the recording operation of the thermal head 1. This causes the thermosensitive recording paper 3 to move in a direction shown by an arrow A2.
With the above-mentioned thermal printer, when the thermal head 1 must be kept off the roller 2 to supply further thermosensitive recording paper or to get rid of a paper jam, the operator manipulates an operating portion 10 so that a projection 11, formed in the operating portion 10, displaces the thermal head 1 against the force applied by the pushing device 6. As an example of the prior art embodiments, Unexamined Japanese Patent Publication No. 176075/1984 discloses an apparatus in which an operating portion is not separate from a supporter of a thermal head. In the thermal printer shown in FIG. 6, the projection 11 applies force to the thermal head 1 at a point which is not on the plane P1. Thus the thermal head 1 may sometimes be distorted in keeping the thermal head 1 off the roller 2. Such a distorted thermal head 1 would not be uniformly pressed against the roller 2, that is, the heating resistance elements 7 is ununiformly pressed on the thermosensitive recording paper 3. This causes irregularity in density of printed characters. There also arises a problem in that a larger operating force is required because the projection 11 applies the force to the thermal head 1 at the point which does not exist on the plane P1.
An object of the present invention is to solve the above-mentioned problems and to provide a thermal recording apparatus with improved operability and enhanced printing quality.